Intensity Compression

Why High-Intensity Workouts Might Be Just What You Need

Research has proven time and again that compressed workouts -- shorter in duration but higher in intensity -- produce equal or better results than less strenuous exertion for longer periods.

New York-based health coach and gym owner Michael Cola never shied away from hard work: two hours a day in the gym sculpted a physique that kept his clients motivated and confident in their trainer’s abilities. Clearly, Cola knew what he was doing. Problem was, he was simply doing too much of it.

“One time, about 12 years ago, I went to the doctor and got some blood work done,” Cola recalls. “My doctor phoned back and asked if I had been working out a lot.” It turned out that Cola’s creatine kinase levels — a measure of waste products in the blood — were through the roof. It’s often used to gauge whether someone has experienced a heart attack.

“He said he had only seen those levels in college players weighing 270,” Cola says. His physician insisted he curb the workouts for two weeks and get re-tested; his levels returned to normal. “That was my turning point. I changed my whole mindset about working out.” Cola went from two hours a day to two hours a week. At 50, he looks better than most 20-year-olds.

Cola’s motivation might be unique, but the less-is-more trend is not: Research has proven time and again that compressed workouts — shorter in duration but higher in intensity — produce equal or better results than less strenuous exertion for longer periods. One famous study conducted by Izumi Tabata in 1996 displayed that four minutes of interval cardiovascular training was superior to 60 minutes of steady-state moderate activity. The former group’s VO2 max, or amount of oxygen you can consume during exertion, was superior.

Carl Foster, Ph.D., Professor of Exercise and Sport Science at the University of Wisconsin-La Crosse, says that high-intensity activity engages more muscle fibers, which essentially doubles the metabolic boost of the exercise. “If you go out and walk or jog, doing some sort of low-intensity exercise for 30 minutes, the only muscle fibers working are the slow-twitch kind in your legs,” he says. “Your fast-twitch muscles, basically half of the fibers, are just along for the ride. They’re just as sedentary as they are when you’re sitting in a chair.”

Sprinting or other kind of interval training — typically defined as bursts of maximal effort followed by a recovery period — engage those fast-twitch fibers; the more muscles are activated, Foster says, the healthier they are. And research is pointing to positive effects, including a lowered risk of diabetes and heart disease.

The same compression technique may also hold true for weightlifting. For most people looking to maintain mass or add strength, Cola refers to a study conducted at Adelphi University that showed one hard set was equal in gains to multiples. (Excluding warm-up sets.) “For the average person, it’s all they really need. It’s insignificant to do more sometimes. There might be a 10% improvement with a second set.” Cola keeps rest periods short; a good weight session should take 30 minutes or less, he says.

'For 95% of the population, two hours a week is all you need.' -Michael Cola

Half an hour in a gym, four days a week — two cardio and two weight sessions — sounds too good to be true, right? For a select portion of the population, it might just be.

“The price you pay is, high intensity isn’t really comfortable,” Foster says. “You have to go in with your eyes open. There’s very good data that the people who have heart attacks when exercising, it’s because of unaccustomed, heavy exercise in the sedentary.” In other words, developing a base of fitness the old-fashioned way is necessary before you begin a compressed schedule. Learning to walk before you run becomes a literal principle. If you experience chest pain or unusual breathlessness, it’s time to stop.

Herold likes to vet clients with a range of motion tests and often uses exercises that are unlikely to result in injury. Cola uses a heart-rate monitor to measure exertion levels before cranking up the resistance. “You work a percentage of their maximum heart rate. One conservative way is to take 220 and subtract the person’s age. Once they’re healthy, you can start pushing them.”

Some fitness trends — CrossFit in particular — often blur the line between weight training and cardio, mixing the two up to create a hybrid that might compress time in the gym even further. But Herold cautions that such synergy comes with a price. “I’ve said that you can’t ride two horses with one ass,” he laughs. “Try to focus on one thing at a time.”

Ultimately, most trainers and physiologists will agree that you should tailor your workout to your goals. For general health, moderate activity for 30 minutes on most days is sufficient. For bodybuilding, more sets equal more muscle volume. If you want to run a marathon, 20-second sprints on a bike won’t be for you. For general fat loss and muscle maintenance, though, intense exercise for brief periods is superior. “For 95% of the population, two hours a week is all you need,” Cola says. “If everyone did that, the world would be a different place.”